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Engine timing start-stop function - GF07.10-P-1041MMW

ENGINE 276.9 in MODEL 212.095 as of model year 2014 

IMPORTANT The Start-Stop function is subdivided into the engine side, the 12-V on-board electrical system side and the hybrid system side scopes.

The partial function "engine timing Start-Stop function" is considered and described from the point of view of the engine timing for the internal combustion engine. Information for partial function "Energy management start/stop function" for the 12-V on-board electrical system is documented in the function description "Energy management function". Information about the partial functions "automatic engine start function" and "automatic engine stop function" from the point of view of the hybrid system can be found over the function description "driving operation function".

IMPORTANT The ME-SFI [ME] control unit (N3/10) continuously performs an SD and assesses the function requirements for the start/stop function. All of the systems participating in the function continuously check their status and transmit this via the Control Area Network (CAN) network to the ME-SFI [ME] control unit. If the function requirements are fulfilled, the driver is notified of readiness to operate of the hybrid system from the green "READY" symbol in the multifunction display (A1p13) in the instrument cluster (A1). Additional information about the required releases for the Start-Stop function are described in the following documents:

Function requirements for engine timing, start/stop function, general points 

engine timing, start/stop function, general points 

Conventional switching off of the internal combustion engine in request by the driver over the electronic ignition lock control unit (N73) is still possible.

Conventional starting of the internal combustion engine is requested by the driver. The internal combustion engine will only be started however it is necessary from the point if view of system optimization.

The ME-SFI [ME] control unit reads in the following sensors and signals for the Start-Stop function:

engine timing, start/stop function, function sequence 

The start/stop function consists of the following partial functions:

IMPORTANT The automatic engine stop in hybrid vehicles is equivalent to electrical driving mode driving.

Additional function requirements for an automatic engine stop 

IMPORTANT The function requirements "internal combustion engine running" includes all function sequences of the fuel low pressure and high-pressure circuit, as described in the function "fuel supply".

Function sequence for automatic engine stop 

The ME-SFI [ME] control unit makes the request via the drive train CAN to the fully integrated transmission control unit (Y3/8n4) for actuation of the wet clutch in order to disconnect the internal combustion engine from the drive. The fully integrated transmission control unit transmits appropriate feedback over the opened wet clutch to the ME-SFI [ME] control unit.

IMPORTANT Additional information concerning actuation of the wet clutch is described in the following document:

The internal combustion engine is switched off by the ME-SFI [ME] control unit if all releases and system conditions of the systems participating in the function are fulfilled.

IMPORTANT More precise information about automatic engine stop related to the HD is described in the following document:

Additional function requirements for an automatic engine start 

Function sequence for automatic engine start 

An automatic engine start is initiated if the vehicle needs energy for the traction which cannot be delivered purely electrically or changes in system conditions require starting of the internal combustion engine.

Start of the internal combustion engine takes place according to the specifications of the aggregate coordinator interface in the ME-SFI [ME] control unit:

In electrical driving mode the internal combustion engine is always first started for an opened wet clutch always over the starter up to a certain rotational speed. The ME-SFI [ME] control unit subsequently requests actuation of the wet clutch via the drive train CAN from the fully integrated transmission control unit in order to connect the internal combustion engine with the transmission.

IMPORTANT Additional information concerning actuation of the wet clutch is described in the following document:

After receiving the respective feedback on the closed wet clutch, the ME-SFI [ME] control unit requests actuation of the electrical machine (A79/1) via hybrid CAN from the power electronics control unit in order to start the internal combustion engine.

IMPORTANT More precise information about automatic engine start related to the HD is described in the following document:

The automatic engine start preferably takes place in a vehicle standstill condition over the electric machine. The internal combustion engine is started over the starter in a vehicle standstill condition if the charge level of the high-voltage battery (A100g1) is not adequate.

The ME-SFI [ME] control unit actuates the following components to start the internal combustion engine:

IMPORTANT Precise information about starting the internal combustion engine with the starter is described in the following document:

  Function schematic for start-stop engine timing   PE07.10-P-2722-97DAU
  Overview of system components for gasoline injection and ignition system with direct injection   GF07.70-P-9998MMO
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